Table 4.

Selected populations and heterogeneity testing.

Time	N^*	Difference of variation to baseline		Effect size (95% CI)	Statistics
		Mean	SD		P value	I², (%)	τ²
Extended analysis (all studies)
M1	2502	3.18	19.7	0.17 (0.12–0.22)	<0.0001	87	0.13
M2	1887	4.27	21.0	0.21 (0.15–0.28)	<0.0001	85	0.11
M3	3014	6.56	22.2	0.30 (0.25–0.35)	<0.0001	84	0.11
M6	2728	8.41	21.3	0.39 (0.33–0.44)	<0.0001	88	0.18
Limited analysis (less #15, #24, #28)
M1	2384	2.13	19.7	0.12 (0.07–0.18)	0.0001	81	0.09
M2	1803	3.11	21.1	0.16 (0.10–0.23)	<0.0001	76	0.06
M3	2896	5.76	22.2	0.27 (0.22–0.32)	<0.0001	80	0.09
M6	2562	8.27	21.4	0.39 (0.33–0.44)	<0.0001	81	0.11
Restricted analysis (less #4, #13, #14, #15, #17, #22, #24, #25, #28)
M1	2127	2.65	19.8	0.14 (0.08–0.20)	<0.0001	75	0.06
M2	1698	3.86	21.5	0.19 (0.12–0.26)	<0.0001	71	0.05
M3	2605	6.36	22.4	0.29 (0.23–0.34)	<0.0001	74	0.06
M6	2296	8.59	21.5	0.40 (0.34–0.45)	<0.0001	78	0.09

^⁎

Intra-articular hyaluronic acid group.